Contradictory reports on air travel and deep venous thrombosis (DVT) risk have documented relative risk varying from 0 to 4.

Increasing public awareness of mortalities resulting from PE following extended airline flights makes further study of this issue warranted.

The Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis (MEGA) study is a case control study that currently has 829 cases and 829 controls enrolled. In this study, travel history with respect to DVT or PE risk was assessed

Materials and Methods

Of the 829 enrolled cases, 465 had DVT while 341 had PE.

Cases were < 70 years of age. Controls were spouses or partners.

All patients were questioned about their travel history in the 3 months prior to their thrombotic event.

The presence of genetic risk factors alone led to a RR of 3. The combination of a genetic risk factor and airplane travel led to a 13-fold increase in RR.

The absolute risk of thrombotic event in a nine week follow-up period was 1:6000 for non-travelers without genetic risk factors, 1:1500 for plane travellers without risk factors and 1:500 for plane travellers with risk factors.

Clinical/Scientific Implications This case control study provides additional evidence supporting the role of immobility during airline travel as a risk factor for DVT/PE. Further study of behavioral modification (exercise), use of pressure stockings or seat size are needed to more precisely define who is at risk from airline flight. Currently a WHO Global Hazards of Travel study is underway which should shed more light on these issues.

Oncolink's ASH Coverage made possible by an unrestricted Educational Grant from Amgen.